I've though for about a decade now, that increasing the pixel resolution of the render would be beneficial with under-sampled lenses.

Interesting. When I was working on my first major photo project, back in 2008, about 40% of my photos were taken with low-resolution point-and-shoot cameras — the rest with a contemporary DSLR.

After lots of trial-and-error, I found out that I got the best results with the PnS cameras when I increased the resolution from the raw files from their native 5 and 6 MP to something larger — 11 MP if I remember, which also happens to be about the size needed for the images. As you mentioned, this makes it easer to correct for lens defects, and it made the images more docile to the extra sharpening that they needed. But I wonder if this was simply due to my lack of good upsizing algorithms — I only had Bicubic Smoother in Photoshop.

But this goes against the trend in smartphone cameras (and Nikon Dx cameras) of oversampling images and demosaicing them to pixel dimensions smaller than the sensor dimensions, or ‘binning’.